Thursday 29 April 2010

Speed humps to help protect Clydevale Bridge from speeding vehicles

Clutha District Council will install speed humps either side of the Clydevale Bridge in order to help protect the bridge from wear caused by speeding heavy vehicles.

New weight restrictions (50% of Class One; 23 ton maximum were placed on the bridge in November 2009 after a detailed historical investigation found it was never initially designed and constructed for Class One (44 ton) loads.

An overweight permit system remains in place to assist qualifying vehicles to continue to use the bridge. However, recent staff observations and speed data obtained from traffic counters at the bridge has verified ongoing concerns that many trucks are still exceeding the 10km/h speed limit, while many light vehicles are exceeding the 70km/h limit.

Chief Executive Charles Hakkaart said the speeding vehicles could have a detrimental effect on the bridge structure and ultimately lead to a bridge failure.

“Speed is a major factor when it comes to the cause of damaged bridges. Many motorists would assume the quicker they get off the bridge then the less wear would occur. However, this isn’t the case.”

Mr Hakkaart said that along with the installation of speed humps, signage and a temporary 10km/h speed zone for all vehicles would be created on each approach to the bridge. This would mean all vehicles would have to reduce their speed to a suitable level before they encountered the speed humps.

“It is anticipated these measures will lead to a large decrease in vehicles speeding across the bridge, and therefore help to prolong its useful life.”

Meanwhile, Mr Hakkaart said that it was envisaged the overweight permit system for the Clydevale Bridge would remain in place for at least the next three to six months while testing on the bridge continues in order to confirm potential for bridge strengthening work. Applications should be made to MWH’s Balclutha office.

The Clydevale Bridge spans the Clutha River about 22km north-west of Balclutha. It is strategically located, linking Clutha with Central Otago, and is the only major bridge over the Clutha River in the district capable of handling wide loads.

Council had already earmarked the bridge for major maintenance/repairs over the next five years at the time of last year’s investigations. Council will continue to hold further discussions with the New Zealand Transport Agency as to determine the best way forward for the long-term future of the bridge. 

ENDS